Magnetron sputtering is widely used in fields such as an integrated circuit, a liquid crystal display, thin film solar energy, and so on. Charged particles (for example argon ions) accelerate to bombard a target material under action of electric field and sputter out a large number of atoms of the target material, neutral target atoms (or molecules) are deposited on a substrate to form a film; electrons are bounded to a plasma region close to a target surface under a combined action of an electric field force and a magnetic field force, and performs reciprocating motion around the target surface under the action of the magnetic field force. The electrons, in a course of motion, constantly collide with the argon atoms, with a large number of argon ions ionized out to bombard the target material, so that the sputtering can be performed uniformly at a high speed, and accordingly a uniform magnetic field is a key that the target material can be uniformly sputtered, and can have a prolonged service life.
The uniform magnetic field can be generated by the high-speed reciprocating motion of a magnet. In a case that the magnet moves to an edge of a rail, it needs to stand still and then return. In a case that the magnet stands still, since a center magnetic field is weak and an edge magnetic field is strong, and a continuous “U”-shaped dent is formed in a position corresponding to a standstill position of the magnet on the target material. FIG. 1 illustrated a schematic diagram of forming the continuous “U”-shaped dent on the target material. With consumption of the target material, the target material is apt to be punctured at a lowest point of the “U”-shaped dent, resulting in an end of the service life of the target material, however, in other positions, the target material has not been fully utilized yet, which results in a lower utilization of the target material.
On the other hand, a thickness of the deposited thin film on the processed substrate is required to be small and uniform, and different parts of the target material are subjected to different intensities and frequencies of bombardment, resulting in different amounts of sputtered material; moreover, rates for depositing the thin film on the processed substrate, and thicknesses of the thin film are both different, which ultimately affects uniformity of the thin film on the processed substrate.